QChart : Update\rescale axis after series update

bronstein87

So, how can i update axis after series update?
Example. Here i create chart:

QChartView* view;
    QChart* chart= new QChart();
    QLineSeries *series = new QLineSeries();
    for(int i=0;i<50000;i++)
    {
        series->append(i,i);
    }
    chart->addSeries(series);
QDateTimeAxis *axisX = new QDateTimeAxis;
    chart->addAxis(axisX, Qt::AlignBottom);
    series->attachAxis(axisX);

    QValueAxis *axisY = new QValueAxis;
    chart->addAxis(axisY, Qt::AlignLeft);
    series->attachAxis(axisY);

Then, in some another place i'm replacing series:

QLineSeries *series=(QLineSeries*)(view->chart()->series().first());
QList<QPointF> list;

    for(int i=0;i<70000;i++)
    {
        list.append(QPointF(i,i-20));
    }
    series->replace(list);

How can i update axis after this?

bronstein87

there is no easy way to do it, so it can be done something like that:

// create a pointer to old chart
    QChart* chartToDelete=NULL;
    if(view->chart())
    {
        chartToDelete=view->chart();
    }
    QChart* chart= new QChart();
    QLineSeries *series = new QLineSeries();
   // here you create Axis, attach them to series and so on



    view->setChart(chart);
    // here delete old chart
    delete chartToDelete;

SamGrant

On the QML side, I do this just by changing the 'min' and 'max' values when updating the series.

Doesn't that work on the C++ side as well:

http://doc.qt.io/qt-5/qvalueaxis.html#max-prop
http://doc.qt.io/qt-5/qvalueaxis.html#min-prop

--Sam